Q 2: minamata disease

Question 1

Mercury (Hg)

Answer 1

Heavy metal
• Exists in several forms: elemental mercury (Hg0),
inorganic mercury and organic mercury
• Hg0 commonly called quicksilver
• Highly toxic to most forms of life

Question 2

what is its state under normal conditions

Answer 2

Hg - mercury

Question 3

sources of mercury

Answer 3

Geologic deposits
– Often found as an ore (HgS)
– High affinity to coal
• Weathering of rock
• Volcanic eruptions
erosion

Question 4

Side Story: The Almadén Mine

Answer 4

World’s largest deposit called the Almadén
deposit, found in Spain
• Spanish convicts and North African slaves worked
the mine in the 1500-1600s

Question 5

other sources from human- (anthropogenic)

Answer 5

fossil fuel (46%), metal production (, 10% artisinal and small scale gold production, cement production, waste incineration, dental amalgam

Question 6

how is hg moved through enviro

Answer 6

biogeochemical cycle- (wind water

Question 7

what is the most dangerous form

Answer 7

organic- bound to carbon

Question 8

toxicity

Answer 8

Specific to chemical form
– Organic vs inorganic
• Also depends on:
– Route of exposure
– Dose
– Age of person exposed (fetus most susceptible)
– Duration of exposure
– Health of person exposed
• We are going to focus on organic mercury
– Specifically, METHYLMERCURY [CH3Hg-X]

Question 9

organic means

Answer 9

carbon

Question 10

Methylmercury (MeHg) Profile- metabolism/ biotransformation and elimination

Answer 10

– Slowly demethylated in intestines and liver- 95% absorbed
• Elimination
– Major routes include bile and feces

Question 11

Absorption

of hg

Answer 11

– Inhalation: vapours of MeHg absorbed
– Oral: highly absorbed in GI tract (approximately 95%)
– Dermal: slow absorption, especially compared to
dimethylmercury**

Question 12

how is methyl merc ditributed in the body

Answer 12

– Distributed throughout body, but especially brain and

fetus

Question 13

Karen Wetterhahn

Answer 13

Side story: Karen Wetterhahn
(dimethylmercury poisoning)
• 48 year old woman who
passed away 10 months
after coming in contact with
an unknown amount of
dimethylmercury
• Karen was a prof at
Dartmouth College who
specialized in toxic metals
• Was using (CH3)2Hg as a
reference material, spilled a
few drops on her glove
• Started experiencing
symptoms 3 months later
– Blood Hg levels 80x the toxic
threshold

Question 14

Bioaccumulates:

Answer 14

concentrations in organism

increase over time

Question 15

Biomagnifies:

Answer 15

concentrations increase up the
food web to higher trophic levels
– Carnivorous fish (freshwater pike, marine sharks,
swordfish) can have Hg tissue concentrations as much
as 10 000 – 100 000 times the concentration of the
water they reside in!)
Cross both the blood-brain barrier and bloodplacental
barrier

Question 16

MINAMATA DISEASE:
A social, environmental, economic,
and political story- WHO

Answer 16

Chisso Corporation Ltd.
– Acetaldehyde plant (MeHg as
a byproduct)
• Inorganic mercury (mercury
salts) used as a catalyst to produce acetaldehyde
through the hydration of acetylene
• This began in 1932 and continued until 1968
• Minamata disease officially discovered in 1956

Question 17

when was minimata desease discovered

Answer 17

1956

Question 18

“Dancing Cat Syndrome”

Answer 18

One of the first indications
that something was going
on in Minamata
• Excessive salivation, violent
movements, death
• Famous “H.I. fluid”
experiments conducted on
cats by Dr. Hosokawa (lifetime
employee and later
superintendant at the Chisso
hospital

Question 19

Timeline of Events cont.

of minamata

Answer 19

1956: The official discovery of Minamata
started with two young girls (ages 3 and 5)
who exhibited strange symptoms, including:
– Clumsiness
– Disorientation
– Difficulty speaking
– Convulsions
• This was just the beginning…

Question 20

Victims of Postnatal Minamata Disease

Answer 20

Early patients diagnosed as
having Minamata disease died
very quickly (acute/subacute
exposure)
• Clinical symptoms common to
most patients included:
– Paraesthesia (mouth/hands/feet)
– Sensory/auditory disturbances
– Constriction of the visual field
(concentric)
– Deafness
– Dysarthria
– Ataxia/Tremors
Many victims of Minamata
Disease were babies born to
pregnant women eating
contaminated fish
• Mothers may or may not
have exhibited any
symptoms
• Clinical manifestations
included:
– Delayed achievement of
development milestones
• Speech and motor function
– Severe cerebral impairment
(cerebral palsy and mental
retardation)

Question 21

Overview of Timeline of Events

Answer 21

Early 1950s
– Fish, birds, cats*
• 1956: Minamata Disease officially
discovered
– Study Group for Minamata Disease
established
• 1959: Organic mercury determined
to be the cause
• 1965: MeHg poisoning occurred in
Niigata, Japan
– Different acetaldehyde plant
• 1968: Japanese government
announced its opinion that
Minamata Disease was indeed
caused by consumption of fish
contaminated with methylmercury
discharged from the chemical
plants… thanks guys

Question 22

summary of minamata

Answer 22

Methylmercury poisoning event in the 1950- 1960s
• Occurred in Minamata, Japan
– A fishing and farming village
• Cause?
– Chisso Corporation Ltd.
• Number of “official”/certified cases? (as of the
year 2001)
– 2955 (1700 of which died)
• Number of “unofficial”/suspected cases?
– 200 000

Question 23

Relief for Minamata Victims?

Answer 23

1. Compensation Agreement (1973)
   – Lump sum of money (medical expenses, pension)
   – However, have to be certified as officially having Minamata Disease
2. Political Settlement (1995)
   – Many people were denied official status, led to lawsuits, conflict, etc.
   – Under this new settlement, people experiencing peripheral limp
   sensory disturbances were entitled to receive a lump sum as well
3. Judicial Damage Compensation (2004)
   – Another lawsuit led to more Minamata victims (who did not fall under
   the original “victim” criteria) being entitled to compensation
4. Additional Measures
   – Better health benefits for those who had already received their lump
   sum

Question 24

in summary- clean up

Answer 24

• Chisso Corporation/the Japanese government
was responsible to:
– Clean up the environment! (Reclamation of Minamata
Bay and surrounding area)
– Environmental monitoring
• Victim compensation (as previously mentioned)
TOTAL COST: 144 BILLION YEN, or
1.4 BILLION CAD

Question 25

ontario

Answer 25

– Wabigoon-English River
System contaminated with Hg
discharged from Dryden Chemicals Ltd

Question 26

Iraq

Answer 26

– Consumption of methylmercury-contaminated bread

Question 27

higher hg in which fish

Answer 27

– Fish highest in Hg include shark, swordfish, king mackerel,
tilefish from Gulf of Mexico (FDA)
– Ex. FDA #s: salmon (2µg/4 ounces) vs. swordfish (147µg/4
ounces)